#define DNSHDRSIZE 12
   
struct dnshdr {
unsigned short int id;

unsigned char  rd:1;           /* recursion desired */
unsigned char  tc:1;           /* truncated message */
unsigned char  aa:1;           /* authoritive answer */
unsigned char  opcode:4;       /* purpose of message */
unsigned char  qr:1;           /* response flag */

unsigned char  rcode:4;        /* response code */
unsigned char  unused:2;       /* unused bits */
unsigned char  pr:1;           /* primary server required (non standard) */
unsigned char  ra:1;           /* recursion available */

unsigned short int que_num;
unsigned short int rep_num;
unsigned short int num_rr;
unsigned short int num_rrsup;
};